Science of Sport: Nature and nurture in Ethiopian endurance running success

In the increasingly competitive world of international sport, identifying the key predictors of success has become a major goal for many sports scientists. And nowhere has the hunt been more focused than in East Africa, where the overwhelming success of male endurance athletes has kept the nature v nurture debate simmering.

Saltin’s famous study comparing Kenyan and Scandinavian athletes suggested that it was the distance the Kenyans travelled to school on foot in childhood that gave them an edge in endurance athletics.

That theory has now received further backing from a major British study comparing the demographic characteristics of Ethiopian athletes with non-athlete controls from the same country.

An additional fascinating finding was that élite Ethiopian distance runners are ethnically distinct from the general Ethiopian population, raising the possibility that genetic factors might also be involved.

Questionnaires seeking information on place of birth, spoken language (by self and grandparents), distance from and method of travel to school were given to 114 male and female members of the Ethiopian national athletics team and 111 Ethiopian controls, none of whom were regularly training for any track or field athletic events. The athletes were separated into three groups for comparison: marathon runners (34), 5-10km runners (42) and other track and field athletes (38).

After analysis, the main findings were as follows:

• In terms of regional distribution, there was a significant excess of athletes, particularly marathoners, from the Arsi and Shewa regions of Ethiopia. 73% of marathon runners hailed from one of these two regions, compared with 43% of 5-10km runners, 29% of track and field athletes and just 15% of controls. To put those figures in context, Arsi is the smallest of Ethiopia’s 13 regions, accounting for less than 5% of the total population, but housing 38% of the marathon athletes in this study;
• The origin of language of all the athlete groups differed significantly from that of the controls. Three separate language categories were used: Semitic, Cushitic and Other; and Cushitic was significantly more predominant in each of the athlete groups than among the controls. The effect was most pronounced in the marathon group, where 75% spoke languages of Cushitic origin compared to 30% of controls;
• In terms of distance travelled to school, the marathon athletes differed significantly from all other groups. 73% of marathoners travelled more than 5k to school each day, compared with 32-40% of the other groups. And marathoners were much more likely to run to school each day than the other groups (68% v 16-31%).

Where does this leave the nature v nurture debate? The findings about travel to school undoubtedly point to environmental influences, as the researchers acknowledge.

‘…the results implicated childhood endurance activity as a key selection pressure in the determination of Ethiopian endurance success,’ they say. ‘With the prevalence of childhood obesity in the United States and Great Britain at an all- time high, and physical activity levels among such populations in stark contrast to the daily aerobic activity of Ethiopian children, these factors may offer an explanation for the success of East-African athletes on the international stage.’

On the other hand, the findings about regional and ethnic origins point to genetic influences. Or do they? The regions of Arsi and Shewa are situated in the central highlands of Ethiopia, intersected by the very same Rift Valley that has been implicated in the success of Kenyan endurance runners. This may seem to support a link between altitude and endurance success. But it doesn’t explain why Arsi is also considerably overrepresented in track and field athletes (18%), who would not be expected to benefit from living and training at altitude.

The researchers put forward an alternative, somewhat more prosaic, hypothesis. ‘One of the senior Ethiopian athletic coaches informed the investigators that most of the marathon athletes would be found to be from Arsi,’ they explain. ‘If those in charge of athletic development believe this, it may cause a self-fulfilling prophecy through talent scouts focusing more attention to this region or through increased regional development of athletics.’

What of the findings about language? The fact that most of the marathoners spoke languages of Cushitic origin (mostly Oromigna, the language of Oromo people) ‘may reflect a high frequency of potential “performance genes” within this particular group.

‘However, it is much more likely,’ the researchers add, ‘that the distinctive ethnic origin of the marathon athletes is a reflection of their geographical distribution, as primarily Oromo people populate Arsi.

‘Although not excluding any genetic influence,’ they conclude, ‘the results of the present study highlight the importance of environment in the determination of endurance athletic success.’

Med Sci Sports Exerc, vol 35, no 10, pp1727-1732

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